Applicators for delivering materials into a body cavity typically comprise an insertion member having an 15 insertion end and a gripper end opposite thereof, and an expulsion member slideably fitted within the insertion member. The gripper end will generally incorporate features to allow a user to more or less securely hold the applicator during use, which includes the following steps: inserting the applicator into a body cavity, expelling a substantially enclosed material contained by the applicator, and withdrawing the applicator from the body.
Attempts have been made to improve the user's ability to manipulate the applicator during use. One approach is to significantly reduce the diameter of the applicator in the gripper end, as can be seen in Whitehead, U.S. Pat. No. 4,508,531. A disadvantage to this approach is while a reduced diameter grip may help in preventing fingers from slipping during insertion, there is little or no resistance offered in the opposite direction during the expulsion step. This is a step with which many users have difficulty.
Another approach to improve the grip of the applicator during use is to incorporate projections, such as in the form of a ring, at the base of the applicator member being inserted into the body. Examples of this approach are disclosed in Voss, U.S. Pat. No. 4,361,150, and in Sartinoranont, U.S. Pat. No. 4,447,222. In order for the projections to function as intended, they must be of significant dimension. However, a number of disadvantages are realized as the projection dimensions increase. One disadvantage is the handling of the applicators during high-speed manufacturing. Applicators are transferred from one position to another many times throughout their manufacture, and the projections can become snagged, severely affecting the output efficiency and quality of the products. Many high-speed manufacturing processes include at least one buffering system that accumulates materials and products between major steps of manipulation and assembly. Applicators with projections generally do not stack neatly (parallel) in the buffering systems. This negatively affects the efficiency of space and transfer, and it potentially creates jams in the process due to applicators being "hung up" in the accumulators or interconnected with adjacent applicators.
A second disadvantage of applicators having projections is related to the packaging of the fully assembled applicators. Just as the applicators will not stack neatly in the buffering systems of high-speed manufacturing equipment, the applicators will not stack neatly in a package of two or more. Either extra packaging material is needed to compensate for non-parallel stacking, or additional equipment and processing steps is required to orient adjacent applicators such that the projections are opposite one another.
Yet another approach to improve the handling of applicators is to increase the friction in the gripper end. This is especially true, as tampon manufacturers are moving toward the use of higher gloss surfaces, which are purported to aid in ease of applicator insertion into a body cavity. An example of this approach is disclosed in Voss, U.S. Pat. No. 3,575,169, wherein an applicator is coated with pulverized stone or sand.
Hagerty, U.S. Pat. No. 5,709,652, discloses an applicator having a plurality of finger-accepting apertures to provide relatively abrupt, finger-accepting edges to frictionally resist movement of a user's finger in response to longitudinal forces on the device. Although a useful contribution to the art, the finger-accepting edges of Hagerty, are limited to the wall thickness of the tubular element.
With many of gripping features described heretofore, the natural tendency of a user is to maximize the friction by applying an increasingly greater normal force, which may result in applicator failure. This failure can be two-fold: one, the applicator can collapse under the normal force and two, the applicator insertion member can increase the amount of friction on an expulsion member slideably fitted within the insertion member, resulting in the inability to expel the material contained by the applicator.
In view of the shortcomings of the prior art, what is needed is an applicator which has substantial resistance to finger slip during use, minimizes applicator collapse and failure, is conducive to high-speed manufacturing, and is conducive to efficient packaging.